Hogwarts faced some major destruction. There is description of entire walls toppling and killing people. There were explosions and fires.
However, as we saw happen after Hagrid's hut was destroyed, things can be fixed. In the prologue we see Harry's kids getting on the Hogwart's Express to go back to school.
in the deathly hallows at the battle of hogwarts
Lupin is dead. He dies in Voldermort's last battle at Hogwarts alongside his wife, Nymphadora Tonks.
They die in the last book in the battle of hogwarts
A lot of people died! People such as- Snape Fred Weasley Lord Voldemort Lupin Tonks Bellatrix Peter Pettigrew Nagini (Voldemort's snake) Colin Creevy (Not shown in the movie I believe, but it IS in the book) and many Hogwarts students and death eaters during the battle at Hogwarts.
He was in Slytherin. In fact, he was the last remaining relative of Salavar Slytherin.
in the deathly hallows at the battle of hogwarts
He returned six times, the last of those was the Battle of Hogwarts in May 1998.
Lupin is dead. He dies in Voldermort's last battle at Hogwarts alongside his wife, Nymphadora Tonks.
30 minutes. Hope this helped! 
They die in the last book in the battle of hogwarts
He dies during the final battle against Voldemort in Hogwarts. He is a werewolf and has a wife and son. Wife: Nymphadora Tonks, dies. His son is Teddy Lupin, who is raised by Andromeda Tonks, Nymphadora's mother and sister to Bellatrix Lestrange and Narcissa Malfoy.
All over Hogwarts and the grounds. The last part takes place in the Great Hall.
In the movie they fought in a courtyard, in the book it was actually in the Great Hall
he and his wife and draco walk away from hogwarts and that is the last we see of them. x
No, it was the last battle of the Napoleonic Wars.
According to the epilogue of the last book, it is rebuilt and it continues education as it was before Voldemort and during his absence.
Harry Potter is not set in the present day - Philopher's Stone is set in the year 1991 and then each book is set one year after the last (ie. Chamber of Secrets is set in 1992, Prisoner of Azkaban is set in 1993 etc)